The present invention relates to a method of degassing or defoaming a liquid with ultrasonic waves, wherein the liquid containing bubble or foam is irradiated with ultrasonic waves in order to eliminate bubble or foam from the liquid, a device using the same and a method of manufacturing a light-sensitive material using the same.
Ordinarily, it is necessary for a certain liquid to be subjected to defoaming.
For example, if a light-sensitive emulsion for light-sensitive photographic film is coated onto a base while bubbles are contained therein, the bubbles cause coating problems. It is, therefore, impossible to form a uniform light-sensitive layer. Streak-shaped or dot-shaped portions which are not sensitive to light at all or where sensitivity is not uniform occurs. Subsequently, it is necessary to defoam the light-sensitive emulsion prior to coating.
As a method of defoaming high viscosity liquids such as a light-sensitive emulsion, a method to defoam the light-sensitive emulsion which is liquid to be defoamed by irradiating it with ultrasonic waves.
In order to enhance the degree of defoaming, various inventions have been made with regard to the form of the defoaming tank which houses a liquid to be defoamed and the strength and direction of the ultrasonic waves. However, no inventions have been able to complete defoaming of the liquid to be defoamed. Further improvement in defoaming effectiveness is demanded.
In addition, recently, photographic coating liquids such as light-sensitive emulsions tend to be condensed, leading to enhanced viscosity. Accordingly, further improvement of the degree of defoaming is demanded.
After laborious study, the present inventors discovered that the bubble-trap effect (in which bubbles are trapped at node portions of the standing waves which occurs in the liquid to be defoamed in the defoaming tank due to irradiation of the ultrasonic waves), which is one of defoaming factor is noticeably dependent upon the condition of the occurrence of the ultrasonic waves such as the stability of the position of node of the standing waves and the difference of sound pressure between node and anti-node of the standing waves.
In addition, they also discovered that the aforesaid condition of the occurrence of ultrasonic waves is influenced by the degree of unsaturation of the density of dissolved air in the liquid to be defoamed under condition of using.
The present inventors discovered as follows: namely, in order to trap bubbles, outputting of the ultrasonic waves generator, which had used to be considered as important is actually not important. As shown in FIG. 1, the difference of the strength of sound pressure between node and anti-node of standing waves in an actual defoaming container .DELTA.I [kgf/cm.sup.2 ] and the frequency SF of the ultrasonic waves [kHz] are, however, important. The relatively larger the difference of the strength of sound pressure between node and anti-node of a standing wave which occurs in the liquid to be defoamed in the defoaming container .DELTA.I [kgf/cm.sup.2 ] is, the larger the force to entrap bubbles so that the degree of defoaming is increased. Strange to say, the lower the frequency of the ultrasonic waves is, the higher the the degree of defoaming is. The present inventors discovered as follows: namely, in order to dissolve bubbles, outputting of the ultrasonic waves generator, which had used to be considered as important is not important. As shown in FIG. 1, the difference of the strength of sound pressure between node and anti-node of a standing wave in actual defoaming container .DELTA.I [kgf/cm.sup.2 ] and frequency SF of the ultrasonic waves [kHz] are important. The relatively larger the difference of the strength of sound pressure between node and anti-node of a standing wave which occurs in the liquid to be defoamed in the defoaming container .DELTA.I [kgf/cm.sup.2 ] is, the larger the force to dissolve bubbles so that the degree of defoaming is increased. Strange to say, the lower the frequency of the ultrasonic waves is, the higher the degree of defoaming is.
In addition, the present inventors discovered that distribution of the standing waves and the form of sound pressure surface of the standing waves are important for defoaming.
As described above, ultrasonic waves defoaming is dependent upon the difference of the strength of sound pressure between node and anti-node of a standing wave which occurs in the liquid to be defoamed in the actual defoaming container .DELTA.I [kgf/cm.sup.2 ]. However, aforesaid the difference of the strength of sound pressure between node and anti-node of a standing wave which occurs in the liquid to be defoamed in the actual defoaming container .DELTA.I [kgf/cm.sup.2 ] is not dependent upon outputting of the ultrasonic waves generator, as previously considered.
The reason for the above is that, even when output by the ultrasonic waves generator is large, there are many cases when the strength of sound pressure between node and anti-node of a standing wave which occurs in the liquid to be defoamed in the actual defoaming container .DELTA.I [kgf/cm.sup.2 ] is extremely small. On the contrary, even when output by the ultrasonic waves generator is small, there are cases in which the strength of sound pressure between node and anti-node of a standing waves which occurs in the liquid to be defoamed in the actual defoaming container .DELTA.I [kgf/cm.sup.2 ] is quite large.
Output by the ultrasonic waves generator means inputted energy to the ultrasonic waves generator. All of the aforesaid energy input is not necessarily vibration output. Secondly, sound pressure of the ultrasonic waves is determined in proportion to the root of the vibration output. However, the aforesaid vibration output is reduced in conversion to heat or vibration in the liquid for transferring ultrasonic waves housed in the container for liquid for transferring aforesaid ultrasonic waves. In other words, there is ultrasonic waves loss. Thirdly, even if the sound pressure of the ultrasonic waves is the same, depending upon the form, size, location and the position of liquid surface of the ultrasonic waves generator, the container for liquid for transferring ultrasonic waves and the defoaming container, the strength of sound pressure between node and anti-node of a standing wave which occurs in the liquid to be defoamed in the actual defoaming container .DELTA.I [kgf/cm.sup.2 ] becomes noticeably changed. Due to the above-mentioned factors, the strength of sound pressure between node and anti-node of a standing wave which occurs in the liquid to be defoamed housed in the actual defoaming container .DELTA.I [kgf/cm.sup.2 ] is not dependent upon output by the ultrasonic waves generator, as has been considered.
Next, the reason for the noticeable change, even if the sound pressure of the ultrasonic waves is the same, depending upon the form, size, location and the position of liquid surface of the ultrasonic waves generator, the container for liquid for transferring ultrasonic waves and the defoaming container, the strength of sound pressure between node and anti-node of a standing wave which occurs in the liquid to be defoamed in the actual defoaming container .DELTA.I [kgf/cm.sup.2 ] will be explained.
Due to ultrasonic waves having the same frequency but transferred to different directions, a standing wave occurs. An actual standing wave in the defoaming container occurs between the ultrasonic wave directly transferred from the ultrasonic waves generator and the ultrasonic waves reflected from the wall of the container. It is normal that the strength and the direction of the reflected ultrasonic waves are different depending upon the form, size, location and the position of the liquid surface of the ultrasonic waves generator, the container for liquid for transferring ultrasonic waves and the defoaming container. Due to this, distribution of the standing waves and the form of the sound pressure surface of the standing waves noticeably influence, the degree of defoaming.
Ordinarily, the strength of sound pressure between node and anti-node of a standing wave .DELTA.I [kgf/cm.sup.2 ] is small. Average sound pressure strength IM [kgf/cm.sup.2 ] is larger than .DELTA.I [kgf/cm.sup.2 ] is small. The contrary condition thereof (.DELTA.I&gt;2.times.IM) cannot be considered. Dissolution of bubbles leaked from the trapped position of the bubbles is also an important factor. Force of the flowing out bubbles is also an important factor. The present inventors attained an invention detailed in the following items, considering the above-mentioned related factors.
Incidentally, in the force of the flowing-out bubbles, viscosity CV [cp], of the liquid to be defoamed, and flow rate FR [mm/sec.], of the defoamed liquid, are important factors. In dissolution of the bubbles, the strength of sound pressure between node and anti-node of a standing wave .DELTA.I [kgf/Cm.sup.2 ], frequency of ultrasonic waves [kHz] and the degree of air unsaturation of the above-mentioned liquid to be defoamed AS [%].